1. Field of the Invention
The present invention relates to a solid electrolytic capacitor formed by mounting a capacitor element on an insulating substrate.
2. Description of Related Art
In a conventional solid electrolytic capacitor, as shown in FIG. 12, a capacitor element 101 is coated with an enclosure resin 102. Inside the enclosure resin 102, one end part 103a of an anode terminal 103 is connected to an anode section 101a of the capacitor element 101, while one end part 104a of a cathode terminal 104 is connected to a cathode section 101b of the capacitor element 101. Both the anode terminal 103 and the cathode terminal 104 are drawn out from the enclosure resin 102, and are bent along an outer peripheral surface of the enclosure resin 102 so that the other end parts 103b, 104b of the terminals 103, 104 are located along a lower surface 102a of the enclosure resin 102. The end parts 103b, 104b of both the terminals 103, 104 located along the lower surface 102a of the enclosure resin 102 form lower surface electrodes of the solid electrolytic capacitor.
In a manufacturing process of the solid electrolytic capacitor described above, required is a complicated step of bending the anode terminal 103 and the cathode terminal 104. In addition, since the enclosure resin 102 of appropriate thickness needs to be interposed between a lower surface of the capacitor element 101 and the lower surface electrodes, there has been a problem of lower occupancy of the capacitor element 101 in the solid electrolytic capacitor, or a problem of greater equivalent series resistance (ESR) or equivalent series inductance (ESL) due to an increase in lengths of the anode terminal 103 and the cathode terminal 104.
Therefore, as shown in FIG. 13, it has been proposed to form the solid electrolytic capacitor by mounting the capacitor element 101 on an insulating substrate 107 (e.g., a printed board) in which an anode terminal 105 and a cathode terminal 106 are formed. In this solid electrolytic capacitor, the anode terminal 105 comprises: a first anode section 105a formed on an upper surface 107a of the insulating substrate 107; a second anode section 105b formed on a lower surface 107b of the insulating substrate 107; and an anode via 105c opening in the insulating substrate 107 to electrically connect the first anode section 105a and the second anode section 105b to each other. The cathode terminal 106 comprises: a first cathode section 106a formed on the upper surface 107a of the insulating substrate 107; a second cathode section 106b formed on the lower surface 107b of the insulating substrate 107; and a cathode via 106c opening in the insulating substrate 107 to electrically connect the first cathode section 106a and the second cathode section 106b to each other.
In the solid electrolytic capacitor described above, to the first anode section 105a, electrically connected is the anode section 101a of the capacitor element 101 through a pad member 108, while, to the first cathode section 106a, electrically connected is the cathode section 101b of the capacitor element 101 by a conductive adhesive. The second anode section 105b and the second cathode section 106b form the lower surface electrodes of the solid electrolytic capacitor.
Thus, by using the insulating substrate 107 to form the solid electrolytic capacitor, a distance from the lower surface of the capacitor element 101 to the lower surface electrodes decreases. Therefore, lengths of the anode terminal 105 and the cathode terminal 106 decrease, resulting in reducing the ESR or ESL. Moreover, due to the employment of the insulating substrate 107 in which the anode terminal 105 and the cathode terminal 106 are formed, it is not necessary to execute the complicated step of bending the anode terminal and the cathode terminal required in the manufacturing process of the solid electrolytic capacitor shown in FIG. 12.
However, in the solid electrolytic capacitor shown in FIG. 13, since the anode section 101a of the capacitor element 101 and the anode terminal 105 are connected to each other by the pad member 108, required is a complicated step of installing the pad member 108 on the anode terminal 105 in the manufacturing process. In addition, the ESR or ESL might increase significantly due to poor connection or the like which occurs between the pad member 108 and the anode terminal 105.